CN114475015A - Electrostatic spraying direct writing system and method with focusing electric field structure - Google Patents
Electrostatic spraying direct writing system and method with focusing electric field structure Download PDFInfo
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- CN114475015A CN114475015A CN202210162126.3A CN202210162126A CN114475015A CN 114475015 A CN114475015 A CN 114475015A CN 202210162126 A CN202210162126 A CN 202210162126A CN 114475015 A CN114475015 A CN 114475015A
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- 230000005684 electric field Effects 0.000 title claims abstract description 52
- 238000007590 electrostatic spraying Methods 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 title claims abstract description 15
- 239000007921 spray Substances 0.000 claims abstract description 73
- 239000000758 substrate Substances 0.000 claims abstract description 47
- 239000007788 liquid Substances 0.000 claims abstract description 44
- 238000005507 spraying Methods 0.000 claims abstract description 8
- 238000007639 printing Methods 0.000 claims description 17
- 238000002347 injection Methods 0.000 claims description 6
- 239000007924 injection Substances 0.000 claims description 6
- 239000011810 insulating material Substances 0.000 claims description 4
- 239000004020 conductor Substances 0.000 claims description 3
- 230000007423 decrease Effects 0.000 claims 1
- 230000005686 electrostatic field Effects 0.000 abstract description 3
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- 239000000463 material Substances 0.000 description 4
- 239000002086 nanomaterial Substances 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000007641 inkjet printing Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 2
- 238000010041 electrostatic spinning Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- -1 oxide Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001523 electrospinning Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
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- 238000002360 preparation method Methods 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J3/00—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed
- B41J3/407—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for marking on special material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/015—Ink jet characterised by the jet generation process
- B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
- B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
- B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
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- Particle Formation And Scattering Control In Inkjet Printers (AREA)
Abstract
The invention provides an electrostatic spraying direct writing system and method with a focusing electric field structure. The system comprises a liquid spray head, a control electrode group connected with at least two electric potentials and a spray substrate with suspended electric potentials. The potential of the liquid spray head can be suspended, or the electrode with the polarity opposite to that of the control electrode group can be connected, the control electrode group comprises a plurality of electrodes with different potentials, not only a radial pull-down electrostatic field with strong enough strength is formed to enable the liquid surface in the spray head to form a Taylor cone to generate electrostatic spraying, but also an axial electric field with strong guidance is formed and is directed to the position of the spraying substrate, which is right opposite to the central shaft of the spray nozzle, so that the jet flow is guided to fall to the point and only falls to the point, and the jet flow deflection to other directions is restrained. The spray substrate then acts as a collector of the droplets formed by the electrostatic jet or jet break-off. The invention can strictly control the drop point of the jet flow or the liquid drop of the electrostatic spraying, and can overcome the difficult problem that stable jet flow is difficult to form on an insulating substrate and a complicated curved surface or an uneven substrate.
Description
Technical Field
The invention relates to the technical field of electrostatic spraying, in particular to an electrostatic spraying direct writing system and method with a focusing electric field structure.
Background
A maskless micro-nano structure direct writing technology based on an electro-hydrodynamic (EHD) principle belongs to one of printing electronic technologies. In 1964, Taylor first proposed a theoretical model that the droplet exhibited a cone shape under the electric field, and thus such a cone was named "Taylor cone". It is characterized by that it can produce jet flow (in theory, it can be up to ten micrometers or even micrometers) with very thin diameter at the top of cone from the jet orifice with larger diameter at the bottom of cone (usually in the order of mm to micrometer), and its jet orifice/jet flow diameter ratio can be up to 100: 1 order of magnitude, and the jet flow size can be conveniently controlled by adjusting parameters such as voltage and the like. Obviously, if electronic circuit printing is carried out by using the jet, the problem of nozzle blockage easily generated by the traditional ink-jet printing method can be well avoided while micron-scale printing precision is achieved. In addition, the method has the advantages of no need of mask plates, wide material applicability, no need of high temperature and high air pressure, simple and convenient control, low cost, suitability for curved surface special-shaped structures and flexible substrates and the like, and is particularly suitable for preparing micro-nano structures and devices. Typical applications of the method include printing micron-sized high-precision flexible conducting circuits on curved surfaces, and further manufacturing high-precision sensors, electronic components, conducting circuits and the like.
However, the conventional electrostatic spraying technique usually connects the substrate as the jet or droplet receiving device to ground and connects the nozzle to high voltage, so as to form high voltage electric field to excite the taylor cone to generate electrostatic spraying, which has three limitations:
(1) if the substrate is made of insulating materials, the substrate cannot be directly grounded or connected with other potentials;
(2) the whole substrate has the same potential, so that the single jet can easily deflect, thereby causing the position printed on the substrate to be difficult to accurately position;
(3) in the case of uneven or complex curved substrate, the surface shape of the substrate may affect the electric field distribution, so that the drop point of the jet or droplet may change, which may cause problems such as discontinuous printing or pattern deformation.
Disclosure of Invention
The purpose of the invention is as follows: the invention provides a system design and a using method for accurately controlling the deflection angle of jet flow in the electrostatic jet direct writing technology aiming at the defects of the traditional electrostatic jet system, thereby avoiding the defects, strictly controlling the falling point of the jet flow or liquid drop of the electrostatic jet, overcoming the difficulty that stable jet flow is difficult to form on an insulating substrate and a complicated curved surface or uneven substrate, being used for electrostatic direct writing of high-viscosity liquid, realizing the on-demand printing of low-viscosity liquid by combining with alternating voltage drive and having strong practical value.
In a first aspect, an electrostatic discharge direct writing system featuring a focusing electrode structure design is provided, the system comprising a head having a potential floating or a potential opposite to a control electrode, a plurality of electrodes, a control electrode set having different potentials, and a discharge substrate having a potential floating. The control electrode group comprises a plurality of electrodes with different electric potentials, a strong enough radial pull-down electrostatic field is formed to enable the liquid surface in the nozzle to form a Taylor cone to generate electrostatic spraying, and meanwhile, a strong-guidance axial electric field is formed and is directed to the position of the spraying substrate, which is opposite to the central axis of the nozzle, so that jet flow is guided to fall to the point and only fall to the point, and jet flow deflection to other directions is inhibited; the spray substrate then acts as a collector for the droplets formed by the electrostatic jet or jet break-off.
In a further embodiment of the first aspect, the control electrode group comprises a plurality of mutually parallel and coaxial ring-shaped electrodes, the number of the ring-shaped electrodes is at least 2, and can be more, the central axis of the ring-shaped electrodes coincides with the central axis of the nozzle, the inner diameter and the outer diameter of the ring are sequentially reduced, the connected electric potential of the ring-shaped electrodes is gradually reduced along the direction away from the nozzle to form a pull-down electric field which is gradually focused towards the central axis, so that the direction of the liquid jet flow is controlled to be only along the central axis direction, and any deflection is restrained and restrained by the focused electric field; the annular electrodes are isolated by air, and an insulating medium can also be added for further reducing the electrode distance.
In a further embodiment of the first aspect, the showerhead is made of insulating material, a needle electrode is placed at its central axis, the bottom of the needle electrode can be pointed to achieve high-pressure ion injection to charge the liquid, and the bottom is close to the liquid surface of the showerhead; the needle electrode is externally connected with a voltage with opposite polarity to the control electrode group, and the voltage value is adjustable; the needle electrode is connected with the highest negative potential, the electrode closest to the spray head in the electrode group is controlled to have the highest positive potential, and the needle electrode and the electrode form a high-voltage electric field together to excite the Taylor cone to realize electrostatic spraying direct writing; the polarities can be reversed according to the requirement.
In a further embodiment of the first aspect, the showerhead is made of metal or other conductive material, and is externally connected with a voltage with opposite polarity to the control electrode group, and the voltage value is adjustable; the potential connected with the spray head is the highest in the negative direction, the voltage carried by the electrode closest to the spray head in the control electrode group is the highest in the positive direction, the two electrodes form a high-voltage electric field together, and the Taylor cone is excited to realize electrostatic spraying direct writing; the polarities can be reversed according to the requirement.
In a further embodiment of the first aspect, alternating current can be used to excite the taylor cone and control the droplet generated after the taylor cone is broken as required, the polarities of the potentials connected to the electrodes included in the control electrode group are always kept consistent and are opposite to the polarities of the needle-shaped electrodes, the polarities of the potentials and the polarities of the needle-shaped electrodes synchronously change along with time to form an alternating electric field, and the breaking of the taylor cone and the size of the droplet generated by the taylor cone can be controlled by controlling the parameters such as the frequency and the amplitude of the alternating electric field, so that the 'spray printing on demand' is realized.
In a second aspect, a focused electric field structure electrostatic spray direct writing method is provided, which comprises the following steps:
applying high voltage to the nozzle and the control electrode group, the high voltage can generate a pull-down electric field to pull the liquid in the nozzle out of the nozzle to form a Taylor cone and a jet of the liquid, the Taylor cone and the jet of the liquid can be guided to the position of the spraying substrate opposite to the central axis of the nozzle under the action of the axial electric field generated by the focusing electrode, so that the liquid is sprayed onto the substrate, and at the moment, the substrate can be sprayed and printed with complex patterns only by using a computer to control a mechanical platform to move the substrate according to a certain mode. The flow rate of the liquid can be automatically controlled by the size of the electric field, and can also be controlled by an additional injection pump and other devices.
Has the advantages that: aiming at the defects of the electrostatic spraying system with the traditional structure, a focusing electrode structure is added between the spray head and the spraying substrate, the direction of liquid jet flow guided by a control electrode group which comprises a plurality of electrodes and is connected with different electric potentials can only be along the central shaft direction, and any deflection is restrained and inhibited by a focusing electric field, so that the falling point of the jet flow or liquid drop of electrostatic spraying can be strictly controlled; the injection substrate is suspended in the air at a potential, so that the problem that stable jet flow is difficult to form on an insulating substrate and a substrate with a complex curved surface or unevenness can be solved; meanwhile, when the system is used, alternating current can be adopted to excite the Taylor cone and control the liquid drops generated after the Taylor cone is broken as required, and the breaking of the Taylor cone and the size of the generated liquid drops can be controlled by controlling the parameters such as the frequency, the amplitude and the like of the alternating electric field, so that the 'spray printing on demand' is realized.
Drawings
Fig. 1 is a schematic view of a conventional electrostatic spray technique.
Fig. 2 is a schematic diagram of three different modes that may exist for the conventional electrostatic spray technique of fig. 1.
Fig. 3 is a schematic diagram of the principle of the present invention.
Fig. 4 is a schematic front view of the direct-write system according to the first embodiment.
Fig. 5 is a schematic front view of the direct-write system mentioned in the second embodiment.
Fig. 6 is a schematic front view of the direct-write system mentioned in the third embodiment.
Number designation in the figures: 1. a spray head; 2. a control electrode group; 3. a spray substrate; 4. a needle electrode; 5-8, mutually parallel and coaxial ring electrodes; 9-11 and high-insulation dielectric layer groups.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.
The applicant believes that conventional electrostatic spray techniques typically involve grounding the substrate as a jet or droplet receiving means and applying a high voltage to the spray head to create a high voltage electric field to excite a taylor cone to produce an electrostatic spray, see figure 1. After the taylor cone is generated based on the EHD principle, three different electrostatic spray modes of electrostatic spraying, electrostatic spinning and electrostatic spot spraying can be generated according to the splitting condition of the jet flow (jet), as shown in fig. 2(a), (b) and (c), three different terminal forms of charged spray, fiber and liquid drop are respectively obtained, and the application is respectively different. In many cases, the jet stream is broken up into mist-like droplets at a certain distance from the cone tip by the action of electrostatic repulsion or the like, and dispersed, that is, an electrostatic spray is formed, as shown in fig. 2 (a). In this case, although very fine droplets can be obtained, they are dispersed in a mist form, and the spray coverage area is much larger than the cross-sectional area of the droplets themselves, which cannot be used for precise ink jet printing. Another situation is that the tangential force perpendicular to the jet direction in the jet formed by the taylor cone causes the jet to whip so that the tail of the jet is not a straight line but a curve of helical disturbances, which is most common in electrospinning, as shown in fig. 2 (b). In this case the jet may be pulled very thin due to the viscous forces of the liquid, but it is difficult to accurately locate where the jet is deposited on the substrate. In recent years, research groups report a method for accurately positioning an electrostatic spinning jet by utilizing the relative motion of a substrate to a spray head and the viscosity of a solution, but the requirements on the viscosity of the solution, the relative motion speed of the substrate and the like are high, and the requirement on high-precision printing of any shape cannot be met. For printing electronic circuits, it is necessary to use an electrostatic dot-jet (E-firing) mode, i.e., controllably breaking the taylor cone into drops falling continuously, and print them in a manner similar to conventional inkjet printing, as shown in fig. 2 (c). To achieve the ideal electrostatic dot-jet mode, the mechanism of jet stream splitting in the taylor cone needs to be studied deeply, the jet stream splitting mechanism is controlled to break to form continuous and uniform small liquid drops, and the continuous and uniform small liquid drops are sequentially deposited on a substrate according to a controllable speed and a controllable position, so that the electrostatic dot-jet mode is called as a 'droplet type discrete printing mode'.
To this end, the applicant has proposed an electrostatic spray direct write system featuring a focusing electrode structure design. See in particular the examples below.
The first embodiment is as follows:
fig. 3 and 4 show an electrostatic spray direct-writing system featuring a focusing electrode structure design, which includes a spray head 1 with a potential floating or switched in a potential opposite to that of a control electrode, a control electrode group 2 including a plurality of electrodes and switched in different potentials, and a spray substrate 3 with a potential floating; the control electrode group 2 comprises a plurality of concentric electrodes with different electric potentials, the inner diameters of the concentric electrodes are gradually reduced, the purpose is to form a radial downward-pulling electrostatic field strong enough to enable the liquid surface in the spray head 1 to form a Taylor cone so as to generate electrostatic spray, and simultaneously form a strong-guidance axial electric field and point to the position of the spray substrate 3 opposite to the central axis of the spray nozzle, so that the jet flow is guided to fall to the point and only fall to the point, and the jet flow deflection to other directions is inhibited; the spray substrate 3 then acts as a collector for the droplets formed by the electrostatic jet or jet break-off. The control electrode group 2 is composed of a plurality of annular electrodes which are parallel to each other and coaxial, the number of the annular electrodes is at least 2, the number of the annular electrodes can be more, the central axis of the annular electrodes coincides with the central axis of the spray head 1, the inner diameter of the annular electrodes is sequentially reduced, the connected electric potential is gradually reduced along the direction far away from the spray head 1 so as to form a pull-down electric field which is gradually focused towards the central axis, therefore, the direction of the liquid jet flow is controlled only along the central axis direction, and any deflection is restrained and restrained by the constraint of the focused electric field (other electrode designs capable of forming the effect are also included in the patent); the annular electrodes are isolated by air, and an insulating medium can also be added for further reducing the electrode distance.
The spray head 1 is made of insulating materials, a needle electrode 4 is arranged at the central axis of the spray head, the bottom of the needle electrode 4 can be pointed to realize high-pressure ion injection to charge liquid, and the bottom is close to the liquid surface of the spray head 1; the needle electrode 4 is externally connected with a voltage with the polarity opposite to that of the control electrode group, and the voltage value is adjustable; the needle electrode 4 is connected with the highest negative potential, the electrode closest to the spray head 1 in the electrode group is controlled to have the highest positive potential, and the needle electrode and the electrode form a high-voltage electric field together to excite the Taylor cone to realize electrostatic spray direct writing; the polarities can be reversed according to the requirement.
The nozzle 1 is made of metal or other conductive materials, is externally connected with a voltage with the polarity opposite to that of the control electrode group, and has an adjustable voltage value; the potential connected with the spray head 1 is the highest in the negative direction, the voltage carried by the electrode closest to the spray head 1 in the electrode group 2 is controlled to be the highest in the positive direction, the high-voltage electric field is formed by the electrode and the electrode, and the Taylor cone is excited to realize electrostatic spraying direct writing; the polarities can be reversed according to the requirement.
Alternating current can be adopted to excite the Taylor cone and control the liquid drop generated after the Taylor cone is broken according to the requirement, the polarity of the electric potential connected with each electrode in the control electrode group is always kept consistent and is opposite to the polarity of the needle electrode 4, the alternating electric field is formed by the electrodes and the needle electrode, the alternating electric field and the needle electrode synchronously change along with time, the breaking of the Taylor cone and the size of the generated liquid drop can be controlled by controlling the frequency, the amplitude and other parameters of the alternating electric field, and the 'spray printing on demand' is realized.
High-insulation media (such as ceramic materials and the like) are added between the annular electrodes of the control electrode group 2 for isolation, so that the electrode distance can be reduced. A high-viscosity liquid is used so that the jet stream is not easily broken although it is elongated, and can directly reach the ejection substrate 3 without breaking, achieving direct writing.
Preferred parameters are as follows: the electrodes 5-8 and the insulating medium layers 9-11 are circular rings, and the inner diameters thereof are as follows in sequence: 7. 5, 3, 1, 6, 4 and 2mm, and the outer diameters thereof are as follows: 10. 8, 6, 4, 9, 7 and 5 mm. The ejection substrate 3 is not electrically connected (floating potential); the spray head is connected with-1 kV (can be adjusted between-10 kV and-0.1 kV); the electrode 5 is connected with +1.5 kV; the electrode 6 is connected with +1.0kV, the electrode 7 is connected with +0.5kV, and the electrode 8 is connected with +0kV (grounding); the total voltage difference between electrode 5 to electrode 8 can be adjusted between 0.1 to 10kV, but electrode 8 is always kept at ground; the thickness of the insulating medium layers of the electrodes 5-8 and 9, 10 and 11 is 0.1mm (the thickness can be adjusted from 0.05mm to 5 mm); the distance from the spray head to the electrode 5 is 5mm (can be adjusted between 1mm and 10 mm); the distance between the electrode 8 and the ejection substrate 3 is 5mm (in principle any value is possible, preferably between 1mm and 10 mm).
Example two:
as shown in fig. 5, a schematic diagram of on-demand printing of low viscosity liquids using ac voltage drive is achieved. At the moment, the polarity of the electric potential connected with each electrode in the control electrode group is always kept consistent and is opposite to the polarity of the needle-shaped electrode 4, the polarity and the polarity of the electric potential are synchronously changed along with time to form an alternating electric field, and the breaking of the Taylor cone and the size of a generated liquid drop can be controlled by controlling the parameters of the frequency, the amplitude and the like of the alternating electric field, so that the 'spray printing on demand' is realized.
Preferred parameters are as follows: the structural parameters are the same as those of the first embodiment, the alternating electric field is a square wave, the amplitude value is the same as that of the first embodiment, and the period of the electrode polarity change along with time is 1ms (the typical value is from 0.1ms to 1000 ms).
Example three:
as shown in FIG. 6, in the first embodiment, the upper and lower surfaces of the insulating dielectric layers 9-11 are plated with metal films (the thickness of the metal film is typically 1 μm, and varies from 100nm to 10 μm, and the upper and lower surfaces are not connected) without providing the electrodes 5-8. Preferred parameters are as follows: the insulating medium layers 9-11 are circular rings, and the inner diameters thereof are as follows in sequence: 6. 4 and 2mm, the outer diameters thereof are as follows: 9. 7 and 5 mm. The ejection substrate 3 is not electrically connected (floating potential); the spray head 1 is connected with-1 kV (can be adjusted between-10 kV and-0.1 kV); the upper surface of the insulating medium layer 9 is connected with +1.5 kV; the lower surface of the insulating medium layer 9 is connected with the upper surface of the insulating medium layer 10 and is connected with +1.0kV, the lower surface of the insulating medium layer 10 and the upper surface of the insulating medium layer 11 are connected with +0.5kV, and the lower surface of the insulating medium layer 10 is connected with +0kV (grounded); the total voltage difference can be adjusted between 0.1 and 10kV, but the lower surface of the insulating medium layer 10 is always grounded; 9. the thickness of the insulating medium layers 10 and 11 is 0.1mm (the thickness can be adjusted from 0.05mm to 5 mm); the distance from the spray head to the upper surface of the insulating medium layer 9 is 5mm (can be adjusted between 1mm and 10 mm); the distance between the lower surface of the insulating medium layer 11 and the ejection substrate 3 is 5mm (in principle, any value is possible, and a value between 1mm and 10mm is recommended).
The present invention can be applied to all aspects of electrostatic spraying for all known and to be extended applications, including but not limited to: ink jet printers, organic circuit printing, display screen printing, integrated circuit printing, biological tissue engineering, liquid atomizers, ionizers, charged particle separation for macromolecular mass spectrometers, maskless lithography, micro-nano material and structure preparation, and the like, all of which form part of the present invention.
The above-mentioned spray head can be made into various shapes and materials of needle tube type, needle-free liquid level excitation type and multi-head array type, etc., the control electrode group can be made into various shapes and materials of square, round, ring, metal and alloy, etc., and the spray base 3 can be made into various materials and shapes of metal, glass, plastics, oxide, organic matter, plane, spherical surface and irregular shape, etc., all of which should form a part of the invention.
The liquid form generated by the electrostatic discharge may be various forms such as droplets, fibers, filaments, beads, and the like, and all of them should form part of the present invention.
On the basis of the invention, the control electrode or the spray substrate 3 can be subdivided into a plurality of sections, a plurality of electrodes with different electric potentials are connected, or different electrode shapes are designed to form different electric field distributions, so as to adjust according to actual needs, realize the precise control of electrostatic droplets, and still form a part of the invention.
As noted above, while the present invention has been shown and described with reference to certain preferred embodiments, it is not to be construed as limited thereto. Various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. Focusing electric field structure electrostatic spray direct-writing system characterized in that includes:
a control electrode group including a plurality of ring-shaped electrodes arranged at predetermined spatial positions;
the potential of the spray head is suspended or the connected polarity of the spray head is opposite to the potential of the control electrode group;
an ejection substrate, the potential of which is suspended;
the annular electrodes arranged in a preset space position are combined to form a control electrode group which is used for forming a preset guiding axial electric field and directing to the position of the spraying substrate opposite to the central shaft of the spray head.
2. The focused e-field structured electrostatic spray direct writing system of claim 1, wherein said set of control electrodes comprises a plurality of ring electrodes of different potentials, parallel and coaxial to each other.
3. The focused electric field structured electrostatic spray direct writing system of claim 1, wherein a central axis of the set of control electrodes coincides with a central axis of the showerhead, and an inner diameter of a ring of the ring-shaped electrode gradually decreases from a position closest to the showerhead to form a pull-down electric field that gradually focuses toward the central axis.
4. The focused electric field structure electrostatic spray direct writing system according to claim 1, wherein adjacent two of the ring electrodes are isolated by air, and the distance between the adjacent two ring electrodes is M.
5. The focused electric field structure electrostatic spray direct-writing system according to claim 4, wherein two adjacent ring electrodes are isolated by an insulating medium, and the distance between the two adjacent ring electrodes is N, wherein N < M.
6. The focused electric field structure electrostatic spray direct writing system according to claim 1 or 3, wherein the nozzle is made of insulating material, a needle electrode is placed at the central axis of the nozzle, and the bottom of the needle electrode is pointed to realize high-voltage ion injection to charge the liquid.
7. The focused electric field structured electrostatic spray direct writing system of claim 6, wherein the bottom of said needle electrode is near the liquid surface of said spray head; the needle electrode is externally connected with a voltage with opposite polarity to the control electrode group, and the voltage value is adjustable;
the needle electrode is connected with the highest negative potential, the electrode closest to the spray head in the electrode group is controlled to have the highest positive potential, and the needle electrode and the electrode form a high-voltage electric field together to excite the Taylor cone to realize electrostatic spraying direct writing.
8. The focused electric field structured electrostatic spray direct-writing system according to claim 1 or 3, wherein the nozzle is made of a conductive material, is externally connected with a voltage with opposite polarity to the control electrode group, and has an adjustable voltage value;
the potential connected with the spray head is the highest in the negative direction, the voltage carried by the electrode closest to the spray head in the control electrode group is the highest in the positive direction, and the control electrode group and the electrode form a high-voltage electric field together to excite the Taylor cone to realize electrostatic spray direct writing.
9. The electrostatic spraying direct writing system of the focusing electric field structure according to any one of claims 1 to 5, wherein alternating current is adopted as required to excite the Taylor cone and control the liquid droplet generated after the Taylor cone is broken, at this time, the polarity of the electric potential connected with each electrode included in the control electrode group is always kept consistent and is opposite to the polarity of the needle electrode, the two electrodes are synchronously changed along with time to form an alternating electric field, and the breaking of the Taylor cone and the size of the generated liquid droplet can be controlled by controlling the parameters such as the frequency and the amplitude of the alternating electric field.
10. The electrostatic spraying direct writing method of the focusing electric field structure is characterized by comprising the following steps of:
step 1, applying a voltage higher than a preset value to the spray head and the control electrode group, wherein the voltage can generate a pull-down electric field to pull liquid in the spray head out of the spray head to form a liquid Taylor cone and jet flow;
step 2, the formed Taylor cone and jet flow are guided to the position of the spraying substrate, which is opposite to the central axis of the spray head, under the action of an axial electric field generated by a focusing electrode, so that liquid is sprayed onto the substrate;
step 3, controlling the mechanical platform to move the substrate according to a preset mode, namely spraying and printing patterns on the substrate; the flow rate of the liquid is controlled by the size of the electric field, or by an additional injection pump or other equipment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210162126.3A CN114475015B (en) | 2022-02-22 | 2022-02-22 | Focusing electric field structure electrostatic spraying direct writing system and direct writing method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210162126.3A CN114475015B (en) | 2022-02-22 | 2022-02-22 | Focusing electric field structure electrostatic spraying direct writing system and direct writing method |
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| CN114475015A true CN114475015A (en) | 2022-05-13 |
| CN114475015B CN114475015B (en) | 2023-03-28 |
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| CN114475015B (en) | 2023-03-28 |
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Denomination of invention: Focused electric field structure electrostatic spray direct writing system and direct writing method Granted publication date: 20230328 Pledgee: Chengdong Branch of Nanjing Bank Co.,Ltd. Pledgor: NANJING WEIHAO TECHNOLOGY CO.,LTD. Registration number: Y2024980007708 |